Transdermal drug delivery devices are designed to deliver a therapeutically effective amount of drug across the skin of a patient. Transdermal drug delivery devices typically involve a carrier (such as a liquid, gel, or solid matrix, or a pressure sensitive adhesive) into which the drug to be delivered is incorporated. Devices known to the art include reservoir type devices involving membranes that control the rate of drug release to the skin and devices involving a dispersion of the drug in a matrix such as a pressure sensitive adhesive. The skin, however, presents a substantial barrier to ingress of foreign substances into the body. It is therefore often desirable or necessary to incorporate certain materials that enhance the rate at which the drug passes through the skin. However, the type of device, suitable components for use in the device, the transdermal flux rate that is suitable, and the suitable formulation components are dependent upon the particular drug to be delivered.
Lerisetron (1-(phenylmethyl)-2-(1-piperazinyl)-1H-benzimidazole) is a known compound disclosed in U.S. Pat. No. 5,256,665. Lerisetron is a serotonin 5HT.sub.3 antagonist. Such antagonists are known to be effective in preventing the nausea and emesis induced by cancer chemotherapy. Other indications for the use of lerisetron include the prophylaxis and treatment of migraine, anxiety and other neuralgic disorders.